In general, this invention relates to rechargeable electrochemical cell terminal configurations as well as chargers having charging terminals designed for use with such cells. More particularly, this invention relates to a charger that includes a first conductive terminal having a central opening therein and a first contact end, and either (a) an insulator positioned within the opening and radially surrounded by the first contact end, the insulator having an insulating contact end portion extending outwardly from the opening, or (b) a second conductive terminal positioned within the opening and radially surrounded by the first contact end, the second conductive terminal having a second contact end portion extending outwardly from and electrically insulated from the first contact end. This invention also relates to a rechargeable electrochemical cell that includes a positive and negative plate, a top end with a perimeter, and an annular charging contact seat integral to and protruding outwardly from the top end and located on the top end away from the perimeter. This invention furthermore relates to combinations of a rechargeable electrochemical cell and a charger therefor.
The batteries used in consumer products can be classified as primary or secondary. The term battery is generally used to describe a single unit comprised of one or more cells. A primary battery is used only once because the active chemicals transformed during the discharge reaction cannot be returned to their original pre-discharge state. Secondary batteries, sometimes called storage batteries or accumulators, can be used repeatedly because the chemical reaction is readily reversible by recharging the battery. Two commonly used primary batteries are the carbon-zinc dry cell and the alkaline cell. Examples of rechargeable, or secondary, batteries are the nickel-cadmium battery, the lead-acid battery, and the nickel-metal hydride battery. Rechargeable battery containers have various shapes and sizes. The nine-volt rechargeable batteries disclosed in U.S. Pat. Nos. 4,213,079 and 4,147,838 are rectangular in shape, whereas cylindrical batteries such as AAA, AA, C, and D batteries are contained in cans. Secondary batteries are oftentimes manufactured to the same size specifications as primary batteries so that the secondaries may be used in place of primary batteries in battery-powered consumer products. This can create a problem for manufacturers of charges. Since the charging of primary batteries can result in adverse effects and potentially hazardous conditions, it is desirable that chargers be designed so that a primary battery inadvertently inserted into place for recharging, cannot be provided charging current.
Furthermore, certain secondary (rechargeable) batteries may be built to have charging current limitations which are different from other identically-sized secondary batteries. In such cases, it would be desirable to configure rechargeable quick-charge batteries so that they may both fit properly into consumer battery-operated products and properly engage in high rate charging circuits which will not accept rechargeable batteries unable to withstand the high/faster rate charging. A charger capable of (1) supplying charging current at a high rate to batteries which can handle the high rate and (2) supplying current at a lower rate to other rechargeable batteries of a corresponding size (which have a slightly different configuration), is also desirable.
Known rechargeable battery terminals and chargers are each deficient in some way and thus unable to produce the desired results discussed above. For example, U.S. Pat. No. 4,382,219 discloses a battery handle adapted for connection to a charger, which must be used with a storage cell in order to prevent improper charging of a nonrechargeable battery. U.S. Pat. No. 4,645,996 discloses a terminal extension permanently added to one of the power terminal contacts of a rechargeable battery so that the battery, in place, can complete the charger "recharging" circuit. However, by permanently adding a terminal extension of the type disclosed, the battery will not fit into battery-operated consumer products designed to accept standard-size primary batteries. U.S. Pat. No. 4,628,242 discloses a removable charging adapter which must be placed on a rechargeable battery to provide a current conducting path between a charger and the rechargeable battery. U.S. Pat. Nos. 4,628,243, 3,506,902, and 4,577,145 disclose terminals located along the side wall of cylindrical rechargeable batteries. This configuration gives a rechargeable battery a charging terminal different from its conventional end discharge terminals.